This invention concerns an engine nozzle arrangement for an aircraft.
According to one aspect of the present invention there is provided an engine nozzle arrangement for an aircraft comprising a nozzle for hot exhaust gases, and a shroud for the stream of hot exhaust gasses emerging from the nozzle, the shroud including means providing an intake for a boundary layer of air for cooling the stream of exhaust gases.
In a preferred form of the invention, the shroud comprises at least one pair of adjustable plates mounted adjacent the hot exhaust nozzle.
One such pair is advantageously movable into a position at least partially blocking the exhaust stream, for providing a reverse thrust. For this purpose, the plates of said pair are conveniently rotatably mounted to provide blocking doors in one rotational position.
Preferably, the same, or another, pair of plates is arranged to be angularly movable relative to an axis of the hot exhaust nozzle for directing the hot exhaust stream for providing vectoring thrust.
According to another aspect of the invention there is provided an engine nozzle arrangement for an aircraft comprising a nozzle for hot exhaust gases, and a shroud including at least one pair of vectoring plates for controlling the direction of the hot exhaust stream.
The invention is particularly advantageous in terms of stealth and enhanced aircraft performance.
In particular, the provision of the shroud over the hot exhaust stream reduces the impact of heat radiation on the surrounding atmosphere and thereby improves infrared (IR) stealth performance.
Further, the supply of a boundary layer of air into the exhaust stream has the advantage of cooling the hot exhaust nozzle and the exhaust stream as well as the shroud, and this again improves IR stealth performance.
Likewise, the boundary layer of cooling air has the effect of reducing the acoustic impact of the hot exhaust stream on the surrounding atmosphere and hence improves acoustic stealth.
The shroud is preferably designed to have a minimal radar cross section. For example, the shroud may be arranged to cover at least a portion of the exhaust nozzle as well as the hot exhaust stream and may thereby provide a reduced radar cross section for the exhaust nozzle and exhaust gases in use.
Aircraft performance may also be significantly improved by the provision of adjustable plates comprising blocking doors for providing reverse thrust and/or vectoring plates for providing vectoring thrust.
The invention has application with both single and dual engine configurations.
A further aspect of the invention features an aircraft including an engine nozzle arrangement as set out above.